Is the concept of nuclear safety the same in France and in China? It seems not. Five weeks ago, the news of a radioactive leak in the Taïshan reactor number 1 raised many concerns. It is the very first French technology reactor, of the EPR type (acronym for European pressurized reactor), to have been put into service in the world. "Abnormal concentrations of certain rare gases in the primary circuit indicate a leakage defect on the cladding surrounding the fuel used in the reactor", then told us EDF, co-operator of 30% of the plant with the Chinese operator. CGN (70%) in the TNPJVC joint venture.
However, the latter had decided to maintain the activity of the reactor despite the alert.
EDF also wanted to be reassuring: “The concentrations are below the regulatory thresholds.
»Problem: these thresholds had been raised to 324 giga becquerels per ton (GBq / t) of water (in France, this threshold is set at 150 GBq / t), in order, precisely, to allow the reactor to remain in the nails and be able to continue to function.
According to our information, the concentrations of these rare gases in the primary circuit had reached 290 GBq / t on May 30.
Unfortunately, concentration levels have continued to rise since then.
In France, shutting down the plant would be necessary
To the point that a TNPJVC board of directors was organized on Thursday, during which EDF expressed its position on the situation. "Analysis of the data available to us shows that the situation is changing," EDF experts confide. In view of these analyzes, EDF's procedures for operating the French nuclear fleet would lead us, in France, to shut down the reactor. "
Officially, the safety of the personnel present on the Taïshan site, like that of the surrounding population, has not been called into question.
But the situation still seems sufficiently worrying to have pushed EDF to sound the alarm bell, in its own way.
"The shutdown of a reactor in France in a similar situation would be necessary in order to precisely characterize the current phenomenon and to stop its development," explains one of the experts interviewed.
As long as the reactor has not been shut down and as long as we have not been able to study the assemblies that were inside, it would be hazardous to go and make forecasts.
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Read also Alert in an EPR nuclear power plant in China: what we know about a possible radioactive leak
Why does the shutdown of the reactor seem to be a consensus today, except for the operator of the plant and the Chinese nuclear safety authority?
First, it is a matter of protecting the rest of the fuel and of the sheaths which surround the rods (metal tubes in which the said fuel is placed), still in good condition.
But also to protect the entire structure all around, what EDF modestly calls “industrial assets”.
Secondly, it is also a question of limiting the radiological activities, and therefore the cleaning operations which must imperatively be carried out on the day when the reactor is finally shut down.
The risk of exposing workers
"The longer we wait, the more we run the risk that other fission products, cesium for example, also contaminate the primary circuit," warns Yves Marignac, nuclear expert and spokesperson for the negaWatt association. However, these radioactive elements will tend to deposit and attach themselves much more durably to the walls, and therefore to expose the workers who will intervene subsequently to much higher levels of radioactivity. "
Elements on which EDF refuses to comment: "In Taïshan, the corresponding decisions belong to TNPJVC", we respond to the management of the French group. Even if we measure perfectly at the headquarters, located avenue de Wagram, in Paris, all the consequences that these leaks could have, beyond Taïshan, on EPR technology. And in particular on the current site in Flamanville, in the Manche department.